1. Field of the Invention
The present invention relates to a method and apparatus for grinding by a grinding stone or cutting by a cutting bite, while the grinding stone or the cutting bite (hereinafter referred to as a processing tool) contacts with a grinding spot or a cutting spot (hereinafter referred to as a processing spot).
2. Description of the Prior Art
For example, in a conventionally used grinding process by a grinding stone, there have been two kinds, one of which is a wet grinding process, which is conducted in the presence of a grinding fluid which is continuously fed to the grinding spot and the other is a dry grinding process, which is conducted in the atmospheric air environment.
In the dry grinding process, there arise problems that a processed surface is affected directly by a grinding heat and thereby burning or cracking occurs on the surface with ease, since a grinding fluid is not used.
On the other hand, in the wet grinding process, there are such advantages as a lubricating effect, a cooling effect and a cleaning effect, but the wet grinding process not only becomes factors of deteriorating a working environment and creating pollution, since high-pressure additives, such as sulfur, phosphorus, chlorine and the like, are included in the grinding fluid in order to especially improve the lubricating effect and a mist of the grinding fluid is scattered around in an atomized condition during the processing, but the cost also becomes tremendously big for treatment of wasted oil, which is a used grinding fluid, and such a high temperature treatment as to give damages to a furnace is required in order not to produce dioxin when the used grinding fluid including chorine is treated. Under such circumstances, development of a more preferable means for grinding which can be effected without the use of a grinding fluid has been expected.
A proposal A on dry grinding which has a cooling effect, non-oxidation effect and a lower grinding resistance is disclosed in the published Unexamined Japanese Patent Application No. Heisei 7-60621.
A proposal B on grinding the surface of a rubber roller, such as a bridle roller, a coating roller, a transport roller and the like, with a grinding stone is disclosed in the published Unexamined Japanese Patent Application No. Showa 61-164779.
The above proposal A has an object to realize the effects of non-oxidation, cooling and lower grinding resistance in a dry grinding by using an inert gas as a working atmosphere. The structure of the system comprises, as shown in FIG. 13, a gastight chamber 100 covering a grinding stone processing section G, a gas tank 101 filled with an inert gas which forms the working atmosphere of the inert gas in the gastight chamber 100 and a circulatory filtration apparatus 102. The circulatory filtration apparatus 102 comprises a filter 102a, a cooler 102b and a blower 102c and an environmental gas in the gastight chamber 100 is circulated in order to be kept in a clean and cooled condition.
Accordingly the proposal A is a technique whose main feature is not to suppress first heat generation which is generation of grinding heat itself at a grinding spot but to suppress second heat generation by a oxidation combustion reaction of grinding chips.
The proposal B is a technique whose feature is to effect a grinding stone process on a workpiece surface in a cold air blast in order to cope with problems arising in a grinding process that polyurethane rubber used as material of rubber lining has poor adaptability to cutting and grinding, is hard to obtain a good surface roughness, good circularity, good straightness and good cylindrical form and besides does not allow the use of a coolant water because of poverty in water resistance and moisture resistance and the technique is conducted by simply applying a cold air blast to the surface of a rubber roller so that the surface may not be softened by a grinding heat. The proposal B has been developed in order to especially cope with a grinding process on a special member which uses polyurethane rubber as structural material, as stated in the text of the specification which is quoted as, if a temperature of the cold air blast is too low, the rubber roller is hardened too much, which causes the surface roughness of a ground surface to be deteriorated. In order to prevent a poor surface roughness, all that has to be done is to suppress an increase in temperature of the surface of the rubber roller by a grinding heat in the grinding process and it is unnecessary to positively cool the surface down to room temperature or lower. In the proposal B, there are no disclosure or suggestions on a technique comprising the use of a cold air blast at a temperature of minus 1.degree. C. or lower or a combination of a cold air blast and a pollution-less oil mist, such as vegetable oil or the like, of fine particles, which are included in the present invention.
Despite the various efforts of improvements on conventional techniques, a problem of environmental sanitation caused by a mist generated from a grinding fluid used in a wet grinding process and a pollution problem arising also in the wet grinding process that relates to a treatment of grinding chips containing a grinding fluid, especially chlorine have not been solved yet. In a dry grinding processing, as the proposal A, a conventional grinding fluid is not used. It might become a cue leading to a solution of the above mentioned problems of environmental sanitation or pollution, but, since the dry grinding process has originally had no consideration to suppress heat generation at a grinding spot, there are risks of reduction in the hardness of a workpiece or lowering of a compression residual stress, which have not still given sufficient investigation for solutions. That is, the proposal A a simple ways for preventing not only oxidation combustion reaction, but also grinding burning and grinding cracking.
The present invention has objects to provide a method and apparatus for pollution-less, high-precision processing without the use of a conventional cutting or grinding fluid.